Non-aqueous liquids, particularly hydrocarbons such as transformer oils, motor oils, transmission fluids, and fuels may become contaminated with particulates during use. These contaminated liquids cause corrosion, wear, mechanical damage to and/or poor performance in the systems in which they are used. Accordingly, it is desirable to detect the presence and quantity of particulates present in these systems to determine when the liquid must be cleaned, processed or replaced.
Several methods exist for detecting particulates in liquids, including non-aqueous liquids. In one method, a sample is taken from the fluid path to a testing facility, mixed with a reagent and the quantity of particulates determined. This method is inefficient as it requires excess time and often leads to inaccurate results caused by contamination during transfer. In another method the liquid is redirected through a slipstream where the liquid is filtered for particulates. The quantity of particulates in the liquid may be inferred by sensing the change in the pressure drop across the filter. This method is reactionary and is ineffective in accurately counting the particulates present and maximizing utilization of the liquid.
In yet another method, a sample is taken, for example, in a slipstream, and the particulates are counted by an optical particle counter. This method is generally highly efficient, and, under the appropriate conditions, extremely accurate. However, counts from optical particle counters are dramatically influenced by the level of water present in a non-aqueous liquid. In many instances, erroneous counts are produced by the presence of water and the operator has no convenient, real time method to know that the counts are wrong. Some conventional solutions solved this problem by using methods, such as heating, to remove the water from the non-aqueous liquid to be tested so that a proper count could be achieved. However, this method may adversely affect the non-aqueous liquid and fails to address the combinatorial effect of water and particulate contamination on non-aqueous liquids.